Harm-removing agent and method for rendering halogen-containing gas harmless and uses thereof

Abstract

The present invention intends to provide an agent and a method for removing harmful gas, which exhibits high harm-removing ability per unit volume for harmful halogen-containing gas contained in the exhaust gas from the etching or cleaning step in the manufacturing process of a semiconductor device, and which is inexpensive. The invention is characterized by that halogen-containing gas is removed using a harm-removing agent comprising a specific iron oxide, an alkaline earth metal compound and activated carbon in the specific amount. In the case where the exhaust gas contains halogen gas such as chlorine or a gas such as sulfur dioxide, the gas is rendered harmless by using in combination a harm-removing agent comprising activated carbon or zeolite.

Description

[0001] This application is an application filed under 35 U.S.C. .sctn.111(a) claiming benefit pursuant to 35 U.S.C. .sctn.119(e) of the filing date of U.S. Provisional Application No. 60 / 216,516 filed on Jul. 6, 2000, pursuant to 35 U.S.C. .sctn.111 (b).[0002] 1. Technical Field[0003] The present invention relates to a harm-removing agent and a method for rendering halogen-containing gas harmless, which can render harmless the exhaust gas containing halogen-containing gas discharged from a dry etching or cleaning step in a manufacturing process of a semiconductor device, and also relates to a method for manufacturing a semiconductor device using them.[0004] 2. Background Art[0005] At the dry etching in the manufacturing process of a semiconductor device, a material subjected to the etching, such as SiO.sub.2, Si, SiW, SiN, Al, GaAs, GaP and InP, is etched using, for example, one or more gas selected from fluorocarbon-type gas, sulfur hexafluoride, hydrogen halide (e.g., hydrogen chl...

AI Technical Summary

Benefits of technology

[0039] (19) A method for manufacturing a semiconductor device, comprising an etching or cleaning step of using at least one gas selected from the group consisting of fluorocarbon, sulfur hexafluoride,. halogen, hydrogen halide and boron trichloride as an etching or cleaning gas, and a harm-removing step of contacting a gas containing halogen-containing gas discharged from said etching or cleaning step with the harm-removing agent described in any one of (1) to (8) above to rendering the halogen-containing gas harmless.

[0047] According to the dry harm-removing method for removing the exhaust gas containing halogen-containing gas discharged, for example, from the dry etching step in the production process of a semiconductor device, the exhaust gas is introduced together with a carrier gas into a harm-removing cylinder filled with various harm-removing agents and contacted with the agent, and only the gas rendered harmless is discharged out of the system. For detecting the break through (end point) of the harm-removing cylinder, a pH test paper which discolors upon contacting (reacting) with halogen-containing gas in general or a harm-removing apparatus in which hue detector agent, pH indicator or the like supported on a support such as alumina and silica gel is integrated with the harm-removing cylinder is widely and commonly employed (used). The conventional agents and methods (1) to (6) for removing harmful gas described above in the Background Art all have a problem that the harm-removing ability for hydrogen halide is low and since hydrogen halide is early leaked to cause discoloration of the end point-detecting agent, the harm-removing cylinder must be frequently exchanged despite their sufficiently high ability of removing other halogen-containing gases, as a result, the cost increases. However, according to the agent and the method for removing harmful gas of the present invention, the frequency of exchanges of the harm-removing agent decreases and the dry etching exhaust gas can be rendered harmless at the low cost, thus, the problems encountered in the production process of a semiconductor device can be overcome.

[0059] The halides of iron and alkaline earth metal produced by the reaction of iron oxide or alkaline earth metal compound in the harm-removing agent with halogen-containing gas are mostly a deliquescent compound except for fluorine-containing compound, therefore, when harmful halogen-containing gas containing almost no fluorine atom is removed, the deliquescent compound gives rise to the clogging of the harm-removing cylinder on great occasions. Accordingly, calcium sulfate may be added to the harm-removing agent of the present invention, whereby even when harmful halogen-containing gas containing almost no fluorine atom is removed, the deliquescence of the harm-removing agent can be prevented successfully. However, when fluorine-containing gas exists together, as the fluoride can prevent the deliquescence, the addition of calcium sulfate is not essential for the present invention.

[0066] The harm-removing agent according to the present invention is characterized by comprising the above-described iron oxide, alkaline earth metal compound and activated carbon in the specific amount. The content ratio of the iron oxide, alkaline earth metal compound and activated carbon blended in the harm-removing agent is such that the iron oxide is from 10 to 40 wt %, the alkaline earth metal compound is from 20 to 80 wt % and the activated carbon is from 10 to 40 wt %, preferably the iron oxide is from 15 to 35 wt %, the alkaline earth metal compound is from 30 to 70 wt % and the activated carbon is from 15 to 35 wt %, more preferably the iron oxide is from 20 to 30 wt %, the alkaline earth metal compound is from 40 to 60 wt % and the activated carbon is from 20 to 30 wt %. With this blending ratio, the properties of each component can be maximally brought out.

[0082] As described in the forgoings, according to the method for removing harmful gas from a dry etching exhaust gas containing halogen-containing gas of the present invention, the exhaust gas is passed through a harm-removing cylinder filled with the harm-removing agent of the present invention alone or together with activated carbon or zeolite in the two-layer structure, whereby the harm-removing method can be improved in the harm-removing ability per unit volume and an exhaust gas containing halogen-containing gas discharged from the etching or cleaning step in the production process of a semiconductor device can be effectively rendered harmless.

[0087] The etching step using a gas such as fluorocarbon or sulfur fluoride can be performed under the dry etching conditions such as plasma etching described, for example, in JP-A-4-121379. Also in this case, gases such as hydrogen halide, silicon halide, tungsten halide and carbonyl halide are similarly generated, but these compounds can be rendered harmless by using the harm-removing agent of the present invention. In the case of performing the etching using sulfur fluoride, sulfur dioxide is generated as a decomposition product in some cases. Even in such a case, the sulfur dioxide can also be effectively removed, as described above, by contacting the exhaust gas with a harm-removing agent comprising zeolite after the treatment with the harm-removing agent of the present invention.

Problems solved by technology

The wet process requires complicated equipment and has a problem in the after-treatment of the absorbing solution or in the operability.

Furthermore, since the exhaust gas is washed with an aqueous solution of alkali such as sodium hydroxide or sodium carbonate, the halogen-containing gas may react with the alkali aqueous solution depending on the case to produce solid matters and therefore the gas outlet line of the treating apparatus may be clogged.

Because of these problems, the wet process is not applied widely.

However, when halogen-containing gas in the dry etching exhaust gas is actually treated, the harm-removing ability decreases in many cases including the methods of (1) to (5) and the harm-removing agent must be frequently exchanged, as a result, the cost for the treatment of dry etching exhaust gas increases.

However, the techniques at present have not yet succeeded in providing an agent and a method capable of rendering halogen-containing gas harmless contained in the dry etching exhaust gas at the low cost while revealing high harm-removing ability (per unit volume), and the development thereof is demanded from many manufacturers of semiconductor device.

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